In many technologies, it is useful to incorporate electronic components over a substrate of the device. Often, these electronic devices are formed from one or more semiconductor layers formed over the substrate. For example, thin film transistors (TFTs) are often formed from semiconductor materials disposed over a substrate in liquid crystal (LC) panels and in organic light-emitting diode (OLED) panels. LC panels and OLED panels are used in LC displays (LCDs) and OLED displays respectively. Additionally, solar panels often comprise a plurality of individual cells that incorporate transistors formed from one or more semiconductor layers formed over a substrate.
In LCD devices, a layer of liquid crystal material is modulated by voltages, which are controlled using electronic components including TFT arrays. Typically, the transistors of the arrays are metal oxide semiconductor (MOS) devices. In solar panels, MOS devices are used for charge storage.
The LCD displays often comprise a glass substrate with the transistors disposed over the glass substrate and beneath a layer of LC material. The transistors are arranged in a patterned array, and are driven by peripheral circuitry to provide desired switching voltages to orient the molecules of the LC material in the desired manner. Moreover, the transistors of the array are often formed directly on or over the glass substrate from a semiconductor material such as silicon or silicon-germanium (SiGe).
In solar panels, charge storage cells may be formed from a matrix of MOS based devices fabricated from either silicon or SiGe formed on a glass substrate. This matrix may be used for selective charge storage of photocurrent generated through photon absorption.
Because the mobility of carriers is generally greater in monocrystalline and polycrystalline semiconductor materials compared to carriers in a semiconductor material in the amorphous phase, it is beneficial to grow crystalline structures on or over the glass substrate of the LCD display or the solar panel. The semiconductor devices may then be fabricated from the monocrystalline or polycrystalline material, resulting in relatively high mobility transistors and other components where high mobility is desired.
While various techniques have been attempted to form crystalline silicon on glass substrates, there are deficiencies. For example, desired substrate materials are damaged using known fabrication methods. Additionally, the resultant material's characteristics are not acceptable. As such, what is needed is a method of fabricating crystalline materials over substrates that overcomes at least the deficiencies of the known techniques.